Known as one example of a fuel cell which has been attracting attention as a clean energy source in recent years is a polymer electrolyte fuel cell (hereinafter referred to as “PEFC (Polymer Electrolyte Fuel Cell)”). In the PEFC, a solid polymer membrane having ionic conductivity is used as a polymer electrolyte. Used as the polymer electrolyte membrane is, for example, a polystyrene-based positive ion-exchange membrane containing a sulfonic acid group, an electrolyte membrane formed by a mixture of a fluorocarbon sulfonic acid and polyvinylidene fluoride, or a perfluoro carbon sulfonic acid membrane.
FIG. 26 is a schematic diagram showing a power generating system using the polymer electrolyte fuel cell. For example, as shown in FIG. 26, a cell stack 99 of the PEFC includes a plurality of single cells 10 each of which is a basic unit and which are stacked, and these single cells 10 are connected to one another in series. Each single cell 10 includes: an anode separator 9 on which a fuel gas channel is formed; a membrane-electrode assembly 5 (hereinafter referred to as “MEA (Membrane Electrode Assembly)”) formed such that the polymer electrolyte membrane is sandwiched between a pair of electrodes that are an anode and a cathode; and a cathode separator 8 on which an oxidizing gas channel is formed. The anode separator 9, the MEA 5, and the cathode separator 8 are stacked in this order.
In the PEFC, when a hydrogen-containing fuel is supplied through the fuel gas channel to the anode, and an oxygen-containing oxidizing agent is supplied through the oxidizing gas channel to the cathode, the fuel and the oxidizing agent react with each other in the anode and the cathode to generate electricity and heat.
In the above PEFC, the MEA 5 is in the form of a thin film. When assembling the cell stack 99, each MEA 5 is difficult to handle. Here, as described in PTL 1 for example, an “MEA member 7” including a frame 6 surrounding the MEA 5 is formed so as to be able to be handled as a single unit, and the handleability of the MEA 5 is improved. A gasket is disposed on the frame to seal between the frame and the anode separator and between the frame and the cathode separator to prevent the fuel gas, the oxidizing gas, and the cooling water from leaking.